text = 'To be or not to be,that is question.'
letters_set = set()
letter_count = {}
for i in text:
    if i.isalpha():
        letters_set.add(i.lower())
        if i.lower() in letter_count:
            letter_count[i.lower()] = letter_count[i.lower()] + 1          #letter_count[] +=1
        else:
            letter_count[i.lower()] = 1
for letter in letters_set:
    count = letter_count[letter]
    print(f"{letter}:{count}")

